2015年4月27日星期一

How your beloved dog could give you a killer disease

They are mankind’s loyal companions. But according to a new study, dogs could be a serious risk to our lives.

Last week, vets warned that many people are overlooking the potentially deadly diseases we could catch from our pets. They carry and spread salmonella, and can infect us with parasites, fungal infections, tapeworm, roundworm and superbugs.

Furious pet owners say the benefits of a dog far outweigh any health risks. So are the vets right? DAVID DERBYSHIRE presents the (rather alarming) evidence...

Food poisoning risk: Dogs don’t just use their tongues to clean themselves, they happily shove their faces into anything smelly- including dead birds, animal carcasses and fox droppings

TUBERCULOSIS

If dogs come into contact with an infected cow, get into a fight with a diseased badger or eat meat infected with the bacteria, they can develop tuberculosis — and pass the potentially deadly lung disease on to you.

The risks are tiny, but real. In 2013, a child caught TB from a family dog in Gloucestershire. The child, who was under ten, made a full recovery, but the dog was put down.

ROUNDWORMS

Two-thirds of public playgrounds are thought to be contaminated with roundworm eggs — stomach-churning parasites that grow up to 14 in long in canine guts.

The eggs are shed in dog mess and survive for months on the ground. If you garden without gloves or eat food you’ve dropped on the floor, the eggs can end up inside you.

The three-second rule — the commonly held belief that if you pick up dropped food immediately it’s safe to eat — doesn’t work here.

Once inside the human body, the larvae cannot grow into adult worms, but migrate to the lungs, liver, eyes and brain, potentially causing serious internal damage and even blindness.

‘Roundworm look like cooked spaghetti and are probably the most common intestinal parasite in dogs,’ says Vicki Larkham, a vet with the People’s Dispensary for Sick Animals.

‘You know if you dog has them because they will be vomiting or you will see the worms.’

DEADLY EIGHT-LEGGED TICKS

Most dog owners have had to remove a tick from their pet.

The voracious eight-legged insects live in bracken and tall grass and jump onto an animal and bury their jaws into the skin.

They can be as small as a poppy seed, but swell to the size of a pea as they gorge on blood.

Getting them out quickly without squeezing their bodies or leaving their mouths behind is essential because many carry the bacteria for Lyme disease, which causes joint pain, lameness and a high fever.

Dogs can’t spread Lyme disease directly to owners, but they can bring ticks into your home.

‘There are treatments from vets that you dab on to kill ticks,’ says Vicki Larkham of the PDSA.

‘It’s unlikely they will carry Lyme disease, but the longer they’re attached, the more likely the risk.’

TAPEWORMS

Tapeworms are revolting. Some varieties grow 30 ft long inside your intestines and live for 20 years.

While most are harmless, one potentially deadly species called echinococcus is putting people at risk in hotspots in Wales, the Welsh borders and the Western Isles.

After dogs eat echinococcus eggs in infected animal carcasses, the worms grow to adulthood in their guts and shed eggs in dog faeces. Dogs spread the eggs to people by licking their faces after cleaning themselves.

In people the tapeworm causes cysts on the liver, lungs or brain, which can grow 12 in across and cause organ failure and even death.

It can take years after infection for symptoms to show.

Caroline Reay, veterinary surgeon at the animal charity Blue Cross, said: ‘You can prevent tapeworm by the regular use of wormers. If you have a dog in an echinococcus hotspot you want to worm it every six weeks.’

SERIOUS FOOD POISONING

Dogs don’t just use their tongues to clean themselves, they happily shove their faces into anything smelly — including dead birds, animal carcasses and fox droppings.

As a result their mouths and guts can be a breeding ground for salmonella and campylobacter — the food poisoning bacteria that can be dangerous for young children and the elderly.

Vicki Larkham says: ‘Unfortunately, dogs like sticking their noses into things, so getting licked on the face and mouth is not a great idea.’

Living With Parasites: tapeworm experiment demo (related)

BUGS ATTACKING YOUR INTESTINES

If your skin is itchy and your dog is suffering from mange, he may have given you scabies

There’s nothing some dogs like more than splashing around in canals and rivers.

But while they’re enjoying a swim, they could also be picking up the waterborne parasite crypto-sporidium, which can cause the disease cryptosporidiosis.

Outside the body, the parasite takes the form of a microscopic capsule or cyst, just five-thousandths of a millimetre long, protected by a tough outer shell. The cysts are immune to chlorine or disinfectants and can survive in water for months.

Once swallowed, the parasites burrow into the intestines, causing diarrhoea, cramps and fever.

If a dog is infected, billions of cysts pass through its system each day. These cysts can get on to fur, tongues or bedding. A human needs to swallow just ten cysts to be infected. Though the chances of a dog passing the disease to you are slim, it’s something to think about the next time a dog licks your face.

VILE PARASITES SPREAD IN FAECES

More than 3,500 people suffer from giardiasis in England and Wales each year.

The disease - which leads to diarrhoea, cramps, belching, flatulence and tiredness - is caused by tiny parasites called giardia, which live in the intestines and are spread in faeces.

Giardia survive for months in water or soil.

Dogs pick up parasites by drinking infected water, rolling in contaminated soil or by licking themselves after contact with a contaminated surface.

Owners can pick up the disease if they let their dogs lick their faces or don’t wash their hands after handling a dog.

If your skin is itchy and your dog is suffering from mange, he may have given you scabies — tiny mites that burrow under the skin in an attempt to lay eggs.

The mites that cause canine scabies are different from the human variety and can’t breed on people.

However, they will still cause temporary discomfort and irritation for a couple of days until they die. If you don’t treat your dog, you can get infected again and again with new generations of the bugs.

‘It’s more common for people to get scabies from other people, but it is possible for the dog variety to infect humans,’ says Vicki Larkham.

‘It’s easily prevented in dogs with a monthly treatment.’

RAT INFECTION

Weil's disease is often spread by rat waste in canals and rivers. If your dog drinks from an infected water source then it can pick up the disease.

Once a pet dog is infected, its urine — and anywhere it urinates — becomes infectious, putting owners at risk. In nine out of ten human cases, it causes mild flu-like symptoms such as headache, aches and chills.

But in 10 per cent it can be life- threatening — and lead to internal bleeding and organ failure.

‘It is completely preventable with vaccination,’ says Vicki Larkham.

‘If your dog has it, you will know about it because they will be pretty poorly. We suggest that dogs with it are hospitalised.’

And while they may increase your risk of some conditions, vets and doctors say dogs are good for your health. Studies have shown that children raised in homes with at least two pets are less likely to suffer from allergies later in life.

And the need to exercise dogs means their owners tend to be healthier and happier.

... and Tiddles can be every bit as dangerous

Cat owners shouldn’t be smug. For while felines are famed for their cleanliness, like dogs, they can carry a host of potentially nasty diseases.

While their chances of picking up nasties are lower than dogs — cats are more hygienic — felines that hunt birds and rodents are exposed to more bacteria and parasites than pooches that rarely go off the leash, and so will spread more disease.

'Cat scratch disease': Even small bites or playful scratches from a kitten can spread a viral infection

DISEASE MAKES BABIES BLIND

If cats eat raw meat or hunt, they are at risk of toxoplasmosis.

The disease is spread by a microscopic single-celled parasite that lives in the guts of animals and which can be passed on in cat litter.

Many infected cats show no signs of illness — though some may suffer fever, weight loss and breathing problems.

If the parasite spreads to people, one in ten will develop mild flu-like symptoms.

More worrying, the parasite can cause brain damage or blindness in unborn babies, which is why pregnant women should avoid cleaning the litter box if they can — and use gloves if they can’t.

A third of the population will get the disease at some point in their life. But only three in 100,000 babies in Britain is harmed by the disease during pregnancy.

FELINE CONJUNCTIVITIS

Conjunctivitis — the infection of the membrane covering the cat’s eyeball — is a common disease, often caused by the cat version of chlamydia.

This bacterial infection can pass from cats to owners, so it’s best to wash hands after handling a sick cat and not let them rub your face.

If owners get infected, symptoms include sore and runny eyes. It can be treated with antibiotics.

CAT SCRATCH DISEASE

A nip from a cat may not be a powerful as a dog bite, but their teeth are sharper and can cause deep wounds capable of penetrating bones and joints.

Conjunctivitis - the infection of the membrane covering the cat’s eyeball - is a common disease, often caused by the cat version of chlamydia

Even small bites or playful scratches from a kitten can spread the viral infection ‘cat scratch disease’. The condition is caused by the bacterium Bartonella henselae, carried by fleas.

It starts with a small blister or bump at the site of the wound, followed by swollen lymph glands and fever a week or so later.

In most cases the disease is mild. But a few victims get more serious symptoms, including lung or liver infections, eye problems and — most rarely of all — brain seizures.

VICIOUS BITES

It may sound like a brand of buttery spread, but pastuerella is a bacterium found in the mouths, noses and throats of most cats.

It can lead to painful and potentially deadly infections if a cat bite breaks the skin.

It can cause sepsis — a potentially life-threatening condition in which the body’s immune system goes crazy and blood supply to vital organs drops.

If not treated quickly it can lead to multiple organ failure and death.

Doctors say people should always seek medical help if they’ve been bitten by an animal.

Many cat bite victims are elderly women stroking or feeding strays. Just one in five cat bites comes from a pet.